Blue Eyes

Blue eyes result
of ancient genetic 'mutation'

Frank Sinatra, Stephen Hawking, Marie Curie and Stephen
Fry all owe their blue eyes to a genetic mutation that likely occurred
between 6,000 and 10,000 years ago, researchers say.

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Scientists
believe they have tracked down the cause of the eye color of all blue-eyed
humans on the planet today.

“Originally, we all had brown eyes”,
said Professor Hans Eiberg from the University of Copenhagen,
who led the team.

Blue
eye color most likely originated from the near east area or northwest
part of the Black Sea region, where the great agriculture migration to
the northern part of Europe took place in the Neolithic periods about
six – 10,000 years ago.

“That is my best guess,” he said. “It could be the northern part of Afghanistan.”

The mutation affected a gene called OCA2 and “literally 'turned off' the ability to produce brown eyes”, he says. OCA2 is involved in the production of melanin, the pigment that gives color to hair, eyes and skin.

The
mutation in the adjacent gene does not switch off the OCA gene entirely
but limits its action, reducing the production of melanin in the iris
of the eye – “diluting” brown eyes to blue.

If the OCA2 gene had
been completely turned off, those who inherited this mutation would be
without melanin in their hair, eyes or skin color - albino.

For
the study, Professor Eiberg’s team examined DNA in blue-eyed
individuals in countries as diverse as Jordan, India, Denmark and
Turkey.

His findings are the latest in a decade of genetic
research, which began in 1996, when Professor Eiberg first implicated
the OCA2 gene as being one of those responsible for eye color.

“They
have all inherited the same switch at exactly the same spot in their
DNA. From this we can conclude that all blue-eyed individuals are
linked to the same ancestor,” said Professor Eiberg, who reports the work in The American Journal of Human Genetics.